Conventionally, a motor is disposed at a central portion of an impeller, and a section for accommodating the motor is mounted on the impeller, which provides a resistance to the flow-in of air, resulting in a degraded efficiency of the blower system. Although the reduction of the section for accommodating the motor causes a decrease in resistance to the flow-in of air, it results in an increase in height of the entire system. In this way, it is difficult to reconcile the thinning of the entire system and the efficiency of the blower system. Furthermore, a gap exists between the impeller and a bell-mouth, and thus a leakage from the inside of the equipment through the gap to an intake port is necessarily generated. This provides a large influence on the efficiency of the blower system.
It has been proposed in JP-A-2005-113730 and JP-A-2005-127311 to mount a motor between an impeller and a bell-mouth. However, a gap between the impeller and the bell-mouth has not been considered in these applications.